Note on drum staff moved via arrow key changes pitch on save / reload

Ubuntu 14.04, GIT commit: d45cc19

First reported in https://musescore.org/en/node/85866

1) load attached score
2) click first note
3) press up arrow to move note to second-to-top space (should match second note)
4) save
5) close
6) reload

Result: note moves to top line

The problem seems to have to do with code I added to correct bad tpc info in certain cases:

https://github.com/musescore/MuseScore/blob/59b72e646f01368b1c6e08c8d33…

This code is causing the pitch of the note to be "fixed" to be consistent with the tpc. Probably my code should not do this for drum staves. However, I am concerned as to why the tpc was wrong in the first place. If you check the two notes in the Object Debugger after step 3, you will see that even though the two notes have the same pitch, they have different tpc's. Apparently the arrow key is not setting tpc correctly on drum staves. I guess tyhis used to be harmless, but it still seems wrong to me.